Plumbing lines are used generally to encompass the supply of necessary liquids to buildings for various purposes and the removal of liquids from buildings and from surrounding areas. Such lines include water supply and the removal of wastes from the buildings as well as waste water from surface run-off. For example, water for building sites is generally supplied by cast iron mains, each section having a familiar "bell shape" on one end into which is inserted the cylindrical end of the adjacent pipe length. This juncture is usually sealed with the use of oakum pounded into the joint which is otherwise unsecured. In time, the pressure of water passing through the line can lead to leaks which, in turn, requires excavation at the leaking joint and repair. Water is supplied to individual structures from the main line by insertion of a T-connector emplaced in the line, the connector usually being of cast iron sealed within the line by usual systems of oakum. The outlet from the T-connector is obviously of a smaller diameter, commensurate in size to provide the required volume of water to the structure. At this point current practice is to use PVC pipe to the structure. Current practice is to use PVC couplings to adhesively connect the pipe lengths to bring the water to the structure. From this point on, piping for delivery of water within the structure may depend upon the size of the structure. Within houses use of copper lines and fittings is most common. In commercial buildings PVC or copper is used depending upon the volume of water involved, i.e., greater volume in high rise buildings dictating PVC because copper piping is generally restricted to diameters of one inch or less and is used in houses, the copper piping is accordingly appropriately coupled by the well known "cold welding" techniques.
Disposal of wastes from structures presents a different problem in the selection of material for the waste lines due to the more corrosive nature of the waste liquids. Such waste liquids usually contain solids which dictates the use of pipes of 3-4 inch diameter and upwards. Because of weight and lack of resistance to corrosion cast iron disposal lines are no longer used. Other than for large diameter major disposal lines concrete supply pipes are rejected because of weight and difficulty in making sufficiently sealed joints. PVC pipe in diameters up to at least 8 inches are now available together with appropriate couplings. At the present time, pipes and couplings are joined by use of adhesives. In large diameter pipes application of adequate amounts of adhesives is time consuming and labor intensive. The corrosive character of waste liquids has been known to react with the adhesives over a period of time which can result in loss of seal integrity.